migrate: don't account swapcache as shmem

swapcache will reach the below code path in migrate_page_move_mapping, and swapcache is accounted as NR_FILE_PAGES but it's not accounted as NR_SHMEM. Hugh pointed out we must use PageSwapCache instead of comparing mapping to &swapper_space, to avoid build failure with CONFIG_SWAP=n. Signed-off-by: Andrea Arcangeli <[email protected]> Acked-by: Hugh Dickins <[email protected]> Cc: [email protected] Signed-off-by: Linus Torvalds <[email protected]>
RyanHsu · Jun 16, 2011 · 99a15e2 · 99a15e2
1 parent 7cc2ed0
commit 99a15e2
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/mm/migrate.c b/mm/migrate.c
@@ -288,7 +288,7 @@ static int migrate_page_move_mapping(struct address_space *mapping,
 	 */
 	__dec_zone_page_state(page, NR_FILE_PAGES);
 	__inc_zone_page_state(newpage, NR_FILE_PAGES);
-	if (PageSwapBacked(page)) {
+	if (!PageSwapCache(page) && PageSwapBacked(page)) {
 		__dec_zone_page_state(page, NR_SHMEM);
 		__inc_zone_page_state(newpage, NR_SHMEM);
 	}